Solar cells are devices that convert solar energy into electrical energy by releasing electric charges that can move in the semiconductor and ultimately flow through an electric load. The phenomenon of producing current in this way is called the photovoltaic effect. Photovoltaic systems are designed around photovoltaic cells. Since a typical photovoltaic cell produces less than 3 watts at approximately 0.5 volt DC, cells must be connected in series-parallel configurations to produce enough power for high-power applications. Arrays of photovoltaic cells form a photovoltaic module, also known as a solar module.
A trend in recent years has been to explore the use of quantum well and quantum dot structures for more effective bandgap tuning and transport control. The advantage of using multi-quantum well structures, for example, in a solar cell is that the effective bandgap can be tuned by varying the thickness of the material layers rather than by changing the composition of the material (a more difficult parameter to control). U.S. Pat. No. 4,688,068 to Chaffin et al., the entirety of which is hereby incorporated by reference herein, describes the general structure of a multi-quantum well solar cell and describes specific applications using III-V compounds. Quantum well structures of this type are typically grown by molecular beam epitaxy (MBE) or metalorganic chemical vapor deposition (MOCVD). These techniques tend to be expensive and involve the use of very toxic chemicals, at least in the case of MOCVD.
Improved thin film and quantum well structures for solar cells and methods of forming solar cells are desired.